Magneto-resistive random access memory with laterally-recessed free layer

ABSTRACT

A method of forming a memory device with a laterally-recessed free layer includes forming a bottom electrode above an electrically conductive structure embedded within an interconnect dielectric material. A magnetic tunnel junction stack is formed above the bottom electrode. Forming the magnetic tunnel junction stack includes forming a magnetic reference layer above the bottom electrode, forming a tunnel barrier layer above the magnetic reference layer, and forming a magnetic free layer above the tunnel barrier layer. Opposed lateral portions of the magnetic free layer are recessed, and sidewall spacers are formed on the recessed opposed lateral portions of the magnetic free layer for confining an active region of the memory device formed by the magnetic free layer and the tunnel barrier layer.

BACKGROUND

The present invention generally relates to the field of magnetic storagedevices, and more particularly to high performance magneto-resistiverandom access memory devices.

Magneto-resistive random access memory (MRAM) is a non-volatile randomaccess memory technology in which data is stored by magnetic storageelements. These magnetic storage elements are typically formed from twoferromagnetic plates, each of which can hold a magnetization, separatedby a thin dielectric layer, i.e., the tunnel barrier. One of the twoplates is a permanent magnetic set to a particular polarity; the otherplate's magnetization can be changed to match that of an external fieldto store memory. Such configuration is known as a magnetic tunneljunction (MTJ) pillar.

For high performance MRAM devices based on perpendicular MTJ pillars,well-defined interfaces and interface control are essential. EmbeddedMTJ pillar structures are usually formed by patterning of blanket MTJstacks. Reactive-ion etch (RIE), and ion beam etch (IBE) processing ofsuch MTJ stacks presents a major challenge, as it typically leads toelectrical shorts due to re-sputtering of underlying thick bottom metallayers onto MTJ stack sidewalls.

SUMMARY

Therefore, there is a need for improved designs and techniques that canprevent the deposition of re-sputtered conductive metal particles fromunderlying (thick) bottom metal layers on sidewalls of the MTJ stack.

According to an embodiment of the present disclosure, a method offorming a memory device includes forming a bottom electrode above anelectrically conductive structure embedded within an interconnectdielectric material, forming a magnetic tunnel junction stack above thebottom electrode, the magnetic tunnel junction stack including amagnetic reference layer above the bottom electrode, a tunnel barrierlayer above the magnetic reference layer, and a magnetic free layerabove the tunnel barrier layer, recessing opposed lateral portions ofthe magnetic free layer, and forming sidewall spacers on the opposedlateral portions of the magnetic free layer for, at least in part,confining an active region formed by the magnetic free layer and thetunnel barrier layer.

According to another embodiment of the present disclosure, a method offorming a memory device includes forming a bottom electrode above anelectrically conductive structure, the electrically conductive structurebeing embedded within an interconnect dielectric material, forming adiffusion barrier liner on a bottom surface and lateral sidewalls of theelectrically conductive structure, forming a magnetic tunnel junctionstack above the bottom electrode, the magnetic tunnel junction stackincluding a magnetic reference layer above the bottom electrode, atunnel barrier layer above the magnetic reference layer, and a magneticfree layer above the tunnel barrier layer, the magnetic free layer beinglaterally recessed with respect to the tunnel barrier layer, and formingsidewall spacers on opposed lateral portions of the magnetic free layerfor, at least in part, confining an active region formed by the magneticfree layer and the tunnel barrier layer.

According to yet another embodiment of the present disclosure, a methodof forming a memory device includes forming a bottom electrode above anelectrically conductive structure embedded within an interconnectdielectric material, forming a magnetic tunnel junction stack above thebottom electrode, the magnetic tunnel junction stack including amagnetic reference layer above the bottom electrode, a tunnel barrierlayer above the magnetic reference layer, and a magnetic free layerabove the tunnel barrier layer, forming a patterned hardmask layer abovethe magnetic free layer, the patterned hardmask layer being formed by abottommost material including a conductive metal, and a topmost materialincluding a sacrificial dielectric material, etching opposed lateralportions of the magnetic free layer, and forming sidewall spacers on theopposed lateral portions of the magnetic free layer for, at least inpart, confining an active region formed by the magnetic free layer andthe tunnel barrier layer.

BRIEF DESCRIPTION OF THE DRAWINGS

The following detailed description, given by way of example and notintended to limit the invention solely thereto, will best be appreciatedin conjunction with the accompanying drawings, in which:

FIG. 1 is a cross-sectional view of a memory device at an intermediatestep during a semiconductor manufacturing process, according to anembodiment of the present disclosure;

FIG. 2 is a cross-sectional view of the memory device depicting forminga magnetic tunnel junction stack above a bottom electrode, according toan embodiment of the present disclosure;

FIG. 3 is a cross-sectional view of the memory device depicting forminga patterned hardmask layer, according to an embodiment of the presentdisclosure;

FIG. 4 is a cross-sectional view of the memory device depicting etchinga magnetic free layer, according to an embodiment of the presentdisclosure;

FIG. 5 is a cross-sectional view of the memory device depicting forminga spacer material, according to an embodiment of the present disclosure;

FIG. 6 is a cross-sectional view of the memory device depicting formingsidewall spacers from the spacer material, according to an embodiment ofthe present disclosure;

FIG. 7 is a cross-sectional view of the memory device depicting etchinga bottom portion of the magnetic tunnel junction stack and bottomelectrode, according to an embodiment of the present disclosure;

FIG. 8 is a cross-sectional view of the memory device depicting forminga dielectric capping layer, according to an embodiment of the presentdisclosure; and

FIG. 9 is a cross-sectional view of the memory device depicting forminga dielectric filling layer, according to an embodiment of the presentdisclosure.

The drawings are not necessarily to scale. The drawings are merelyschematic representations, not intended to portray specific parametersof the invention. The drawings are intended to depict only typicalembodiments of the invention. In the drawings, like numbering representslike elements.

DETAILED DESCRIPTION

Detailed embodiments of the claimed structures and methods are disclosedherein; however, it can be understood that the disclosed embodiments aremerely illustrative of the claimed structures and methods that may beembodied in various forms. This invention may, however, be embodied inmany different forms and should not be construed as limited to theexemplary embodiments set forth herein. In the description, details ofwell-known features and techniques may be omitted to avoid unnecessarilyobscuring the presented embodiments.

For purposes of the description hereinafter, terms such as “upper”,“lower”, “right”, “left”, “vertical”, “horizontal”, “top”, “bottom”, andderivatives thereof shall relate to the disclosed structures andmethods, as oriented in the drawing figures. Terms such as “above”,“overlying”, “atop”, “on top”, “positioned on” or “positioned atop” meanthat a first element, such as a first structure, is present on a secondelement, such as a second structure, wherein intervening elements, suchas an interface structure may be present between the first element andthe second element. The term “direct contact” means that a firstelement, such as a first structure, and a second element, such as asecond structure, are connected without any intermediary conducting,insulating or semiconductor layers at the interface of the two elements.

It will be understood that, although the terms first, second, etc. canbe used herein to describe various elements, these elements should notbe limited by these terms. These terms are only used to distinguish oneelement from another element. Thus, a first element discussed belowcould be termed a second element without departing from the scope of thepresent concept.

In the interest of not obscuring the presentation of embodiments of thepresent invention, in the following detailed description, someprocessing steps or operations that are known in the art may have beencombined together for presentation and for illustration purposes and insome instances may have not been described in detail. In otherinstances, some processing steps or operations that are known in the artmay not be described at all. It should be understood that the followingdescription is rather focused on the distinctive features or elements ofvarious embodiments of the present invention.

MRAM devices include cells or magnetic storage elements for storing datahaving a magnetically hard layer (i.e., the reference layer) and amagnetically soft layer (i.e., the free layer) separated by a thindielectric layer (i.e., the tunnel barrier). This configuration is knownas a magnetic tunnel junction (MTJ) pillar. MTJ pillar structurestypically include a cobalt (Co)-based synthetic anti-ferromagnet (SAF),a CoFeB-based reference layer, a MgO-based tunnel barrier, a CoFeB-basedfree layer, and cap layers containing materials such as tantalum (Ta)and/or ruthenium (Ru). As mentioned above, embedded MTJ pillarstructures are usually formed by patterning of blanket MTJ stacks.Reactive-ion etch (RIE), and ion beam etch (IBE) processing of such MTJstacks presents a major challenge, as it typically leads to shorts dueto re-sputtering of thick bottom metal layers onto MTJ stack sidewalls.

Embodiments of the present disclosure generally relates to the field ofmagnetic storage devices, and more particularly to high performance MRAMdevices based on perpendicular MTJ structures. Embodiments of thepresent disclosure provide an MRAM device with an embedded MTJ pillarstructure, and a method of making the same, in which a free layer of theMTJ pillar structure is laterally recessed and surrounded by adielectric material to prevent re-sputtered conductive metal particlesfrom depositing on the tunnel barrier material of the MTJ pillarstructure. Stated differently, the proposed embodiments may preventback-sputtering of conductive metal particles during etching of the MTJpillar structure by recessing the free layer of the MTJ pillar structureand depositing a dielectric material around the recessed free layer.This may reduce the risk of electrical shorts which is a common failuremode in traditional MTJ configurations, thereby increasing devicereliability.

Embodiments by which the MTJ pillar structure with laterally-recessedfree layer can be formed is described in detailed below by referring tothe accompanying drawings in FIGS. 1-9 .

Referring now to FIG. 1 , a cross-sectional view of a memory device 100at an intermediate step during a semiconductor manufacturing process isshown, according to an embodiment of the present disclosure. The memorydevice 100 may include any MTJ-containing device such as, for example,MRAM, spin-transfer torque (STT) MRAM, spin-orbit torque (SOT) MRAM andthe like. In the embodiment of FIG. 1 , the memory device 100 is an MRAMdevice based on a perpendicular MTJ pillar structure.

According to an embodiment, the memory device 100 includes anelectrically conductive structure 106 that is embedded in aninterconnect dielectric material layer 102. A diffusion barrier liner104 can be formed on sidewalls and a bottom wall of the electricallyconductive structure 106, as shown in the figure. Collectively, theelectrically conductive structure 106, the diffusion barrier liner 104,and the interconnect dielectric material layer 102 provide aninterconnect level. It should be noted that at least one otherinterconnect level and/or a middle-of-the-line (MOL) level may belocated beneath the interconnect level including the interconnectdielectric material layer 102, the electrically conductive structure106, and the diffusion barrier liner 104. These other levels are notshown for clarity.

The interconnect dielectric material layer 102 can be composed of anyinterconnect dielectric material including, for example, silicondioxide, silsesquioxanes, C doped oxides (i.e., organosilicates) thatincludes atoms of Si, C, 0 and H, thermosetting polyarylene ethers, ormultilayers thereof. The term “polyarylene” is used in this applicationto denote aryl moieties or inertly substituted aryl moieties which arelinked together by bonds, fused rings, or inert linking groups such as,for example, oxygen, sulfur, sulfone, sulfoxide, carbonyl and the like.

The electrically conductive structure 106 is composed of an electricallyconductive metal or metal alloy. Examples of electrically conductivematerials that may be used in the present application include copper(Cu), aluminum (Al), or tungsten (W), while an example of anelectrically conductive metal alloy is a Cu—Al alloy.

The diffusion barrier liner 104 is formed along the sidewalls and bottomwall of the electrically conductive structure 106. In some embodiments,no diffusion barrier liner is present. The diffusion barrier liner 104is composed of a diffusion barrier material (i.e., a material thatserves as a barrier to prevent a conductive material such as copper fromdiffusing there through). Examples of diffusion barrier materials thatcan be used in providing the diffusion barrier liner 104 may include,but are not limited to, Ta, TaN, Ti, TiN, Ru, RuN, RuTa, RuTaN, W, orWN. In some embodiments, the diffusion barrier liner 104 may include amaterial stack of diffusion barrier materials. In one example, thediffusion barrier material may be composed of a stack of Ta/TaN.

The interconnect level including the interconnect dielectric materiallayer 102, the electrically conductive structure 106, and the diffusionbarrier liner 104 may be formed utilizing conventional processes thatare well-known to those skilled in the art including, for example, adamascene process. So as not to obscure the method of the presentapplication, the techniques used to form the interconnect levelincluding the interconnect dielectric material layer 102, theelectrically conductive structure 106, and the diffusion barrier liner104 are not provided herein.

With continued reference to FIG. 1 , a bottom electrode 110 is formedabove top surfaces of the interconnect dielectric material layer 102,the electrically conductive structure 106, and the diffusion barrierliner 104. As shown in the figure, the bottom electrode 110 covers anentirety of topmost surfaces of the interconnect dielectric materiallayer 102, the electrically conductive structure 106, and the diffusionbarrier liner 104.

The bottom electrode 110 may be composed of a conductive material suchas, for example, Ta, TaN, Ti, TiN, Ru, RuN, RuTa, RuTaN, Co, CoWP, CoN,W, WN or any combination thereof. The bottom electrode 110 may have athickness varying from approximately 2 nm to approximately 25 nm andranges there between, although a thickness less than 2 nm and greaterthan 25 nm may be acceptable. The bottom electrode 110 may be formed bya deposition process such as, for example, sputtering, atomic layerdeposition (ALD), chemical vapor deposition (CVD), plasma enhancedchemical vapor deposition (PECVD) or physical vapor deposition (PVD). Anetch back process, a planarization process (such as, for example,chemical mechanical polishing), or a patterning process (such as, forexample, lithography and etching) may follow the deposition of theconductive material that provides the bottom electrode 110.

In some embodiments (not shown), the bottom electrode 110 is located ona recessed surface of the electrically conductive structure 106. In suchembodiments, prior to forming the bottom electrode 110, an upper portionof the electrically conductive structure 106 is removed utilizing arecess etching process, and thereafter the bottom electrode 110 isformed upon the recessed surface of the electrically conductivestructure 106. Thus, the bottom electrode 110 would be located on anentirety of the recessed topmost surface of the electrically conductivestructure 106. In such embodiments, a topmost surface of the bottomelectrode 110 must not be coplanar with a topmost surface of theinterconnect dielectric material layer 102. Instead, the topmost surfaceof the bottom electrode 110 should be located approximately 2 nm toapproximately 40 nm above (in z-direction) the topmost surface of theinterconnect dielectric material 102. And, a bottommost surface ofbottom electrode 110 should be located approximately 2 nm toapproximately 40 nm below (in z-direction) the topmost surface of theinterconnect dielectric material 102.

In some embodiments, a conductive layer (not shown) including anyconductive material can be formed above the bottom electrode 110. Insome embodiments, a material that has, or combination of materials thathave, a lower atomic weight than the conductive material that providesthe bottom electrode 110 can be used as the conductive layer (notshown). Typically, the conductive material that provides the conductivelayer has a lower sticking coefficient than that of the bottom electrode110. Illustrative examples of conductive materials that can be used asthe conductive layer can include one of the conductive materialsmentioned above for the bottom electrode 110 with the proviso that theselected conductive material of the conductive layer (not shown) has alower atomic weight than the conductive material of bottom electrode110. In one example, and when the bottom electrode 110 is composed ofTaN, then the conductive layer can be composed of Ti or TiN, Nb or NbN.

If present, the conductive layer (not shown) can be formed by adeposition process such as, for example, sputtering, atomic layerdeposition (ALD), chemical vapor deposition (CVD), plasma enhancedchemical vapor deposition (PECVD) or physical vapor deposition (PVD).The thickness of the conductive layer may be from 20 nm to 500 nm. Otherthicknesses besides the specified range can also be employed as thethickness of the conductive layer.

Referring now to FIG. 2 , a cross-sectional view of the memory device100 is shown depicting forming an MTJ stack 200 above the bottomelectrode 110, according to an embodiment of the present disclosure. TheMTJ stack 200 may include at least a magnetic reference layer 210, atunnel barrier layer 220, and a magnetic free layer 230 as depicted inFIG. 2 . It should be noted that other MTJ stack 200 configurations arepossible such as, for example, the magnetic free layer 230 being locatedat the bottom of the MTJ stack 200 and the magnetic reference layer 210being at the top of the MTJ stack 200.

In some embodiments, the MTJ stack 200 may also include a non-magneticspacer layer (not shown) located on the magnetic free layer, a secondmagnetic free layer located on the non-magnetic spacer layer, and/or aMTJ cap layer located on the magnetic free layer 230 or on the secondmagnetic free layer. The various material layers of the MTJ stack 200can be formed by utilizing one or more deposition processes such as, forexample, plating, sputtering, plasma enhanced atomic layer deposition(PEALD), plasma enhanced chemical vapor deposition (PECVD) or physicalvapor deposition (PVD).

The magnetic reference layer 210 has a fixed magnetization. The magneticreference layer 210 may be composed of a metal or metal alloy (or astack thereof) that includes one or more metals exhibiting high spinpolarization. In alternative embodiments, exemplary metals for theformation of the magnetic reference layer 210 may include iron, nickel,cobalt, chromium, boron, or manganese. Exemplary metal alloys mayinclude the metals exemplified by the above. In another embodiment, themagnetic reference layer 210 may be a multilayer arrangement having (1)a high spin polarization region formed from a metal and/or metal alloyusing the metals mentioned above, and (2) a region constructed of amaterial or materials that exhibit strong perpendicular magneticanisotropy (strong PMA). Exemplary materials with strong PMA that may beused include a metal such as cobalt, nickel, platinum, palladium,iridium, or ruthenium, and may be arranged as alternating layers. Thestrong PMA region may also include alloys that exhibit strong PMA, withexemplary alloys including cobalt-iron-terbium, cobalt-iron-gadolinium,cobalt-chromium-platinum, cobalt-platinum, cobalt-palladium,iron-platinum, and/or iron-palladium. The alloys may be arranged asalternating layers. In one embodiment, combinations of these materialsand regions may also be employed.

The tunnel barrier layer 220 is composed of an insulator material and isformed at such a thickness as to provide an appropriate tunnelingresistance. Exemplary materials for the tunnel barrier layer 220 mayinclude magnesium oxide, aluminum oxide, and titanium oxide, ormaterials of higher electrical tunnel conductance, such assemiconductors or low-bandgap insulators.

The magnetic free layer 230 may be composed of a magnetic material (or astack of magnetic materials) with a magnetization that can be changed inorientation relative to the magnetization orientation of the magneticreference layer 210. Exemplary magnetic materials for the magnetic freelayer 230 include alloys and/or multilayers of cobalt, iron, alloys ofcobalt-iron, nickel, alloys of nickel-iron, and alloys ofcobalt-iron-boron.

It should be noted that some elements and/or features of the memorydevice 100 are illustrated in the figures but not described in detail inorder to avoid unnecessarily obscuring the presented embodiments. Forillustration purposes only, without intent of limitation, only one MTJstack 200 with a corresponding bottom electrode 110 is depicted in thememory device 100. As may be understood by those skilled in the art, thememory device 100 may include more than one MTJ stack 200.

Referring now to FIG. 3 , a cross-sectional view of the memory device100 is shown depicting forming a patterned hardmask layer 330, accordingto an embodiment of the present disclosure.

The patterned hardmask layer 330 may be composed of a metal (not shown)such as TaN, TaAlN, WN as the bottommost material, and a dielectricmaterial (not shown) such as silicon dioxide, silicon nitride, siliconcarbide, and the like, as the topmost material. The hardmask layer 330can be deposited by any suitable deposition method known in the art. Itshould be noted that the metal layer in the patterned hardmask layer 330is not sacrificial, while the dielectric layer in the patterned hardmasklayer 330 is sacrificial, in that the dielectric layer will be removedafter completion of the patterning process. In some embodiments, toplayers (not shown) of the MTJ stack 200 may act as both a hardmask foretching the MTJ stack 200 and as an interlayer conductor channel.

A (vertical) thickness of the hardmask layer 330 may vary betweenapproximately 10 nm to approximately 100 nm, although other thicknessesabove or below this range may be used as desired for a particularapplication. It should be noted that the process of forming andpatterning the hardmask layer 330 for etching the underlying MTJ stack200 is standard and well known in the art.

Referring now to FIG. 4 , a cross-sectional view of the memory device100 depicting etching the magnetic free layer 230 is shown, according toan embodiment of the present disclosure. In this embodiment, a dryetching technique such as a reactive-ion etching (RIE) or ion beametching (IBE) can be implemented to recess the magnetic free layer 230,as depicted in the figure. The magnetic free layer 230 is laterallyrecessed until a (horizontal) thickness of the magnetic free layer 230is between approximately 200 nm to approximately 10 nm.

The process of patterning the MTJ stack 200 consists of steps well-knownin the art, which generally include forming a pattern on a photoresistlayer (not shown) that is transferred to the patterned hardmask layer330 and used to pattern the underlying MTJ stack 200 (and bottomelectrode 110) via any suitable etching technique. In this embodiment,patterning of the MTJ stack 200 starts by laterally recessing themagnetic free layer 230, then the etching process is stopped at anuppermost surface of the tunnel barrier layer 220. As will be describedbelow, a spacer material is deposited on the memory device 100 afterrecessing the magnetic free layer 230.

Alternatively, or additionally, in some embodiments, the etching processmay continue until an uppermost surface of the magnetic reference layer210. Thus, in such instances, the tunnel barrier layer 220 may also belaterally recessed. In some embodiments, the tunnel barrier layer 220can be partially or completely removed during the etching process.

Referring now to FIG. 5 , a cross-sectional view of the memory device100 depicting the formation of a spacer material 510 is shown, accordingto an embodiment of the present disclosure. The spacer material 510 canbe deposited on the memory device 100 and subsequently etched (FIG. 6 )to form sidewall spacers 610 as configured in FIG. 6 .

The spacer material 510 may include an insulator material such as anoxide, nitride, oxynitride, silicon carbon oxynitride, silicon boronoxynitride, low-k dielectric, or any combination thereof. Standarddeposition and etching techniques may be used to form the spacermaterial 510.

Referring now to FIG. 6 , a cross-sectional view of the memory device100 depicting forming sidewall spacers 610 from the spacer material 510(FIG. 5 ) is shown, according to an embodiment of the presentdisclosure. The spacer material 510 (FIG. 5 ) can be etched using, forexample, an anisotropic etch, to form the sidewall spacers 610. As knownby those skilled in the art, the insulator material forming the spacermaterial 510 (FIG. 5 ) is removed from all horizontal surfaces of thememory device 100 during the etching process.

According to an embodiment, the sidewall spacers 610 are positioned onopposing sidewalls of the magnetic free layer 230 and a bottom portionof the patterned hardmask layer 330. A bottom surface of the sidewallspacers 610 is directly above the tunnel barrier layer 220. Thus, thesidewall spacers 610 confine an active region of the memory device 100formed by the magnetic free layer 230 and portions of the tunnel barrierlayer 220 underneath the magnetic free layer 230. This configuration mayprevent back-sputtering of metal particles from bottom metal layers,such as the bottom electrode 110, onto the tunnel barrier layer 220during patterning of the MTJ stack 200, thus preventing electricalshorts or leakage current between bottom metal layers and top metallayers within the MTJ stack 200.

According to an embodiment, a (horizontal) thickness of the sidewallspacers 610 may vary between approximately 3 nm to approximately 40 nm,although other thicknesses above or below this range may be used asdesired for a particular application.

Referring now to FIG. 7 , a cross-sectional view of the memory device100 depicting etching a bottom portion of the MTJ stack 200 and thebottom electrode 110 is shown, according to an embodiment of the presentdisclosure.

In this embodiment, patterning of the MTJ stack 200 continues by etchingremaining bottom layers of the MTJ stack 200 including the magneticreference layer 210 and the tunnel barrier layer 220. Any suitableetching technique can be used to recess the magnetic reference layer 210and the tunnel barrier layer 220. For example, the magnetic referencelayer 210 and the tunnel barrier layer 220 can be recessed using a dryetching technique such as reactive ion etch (RIE), or ion beam etch(IBE). A (horizontal) thickness of the sidewall spacers 610 togetherwith a thickness of the magnetic free layer 230 indicate a thickness ofthe magnetic reference layer 210 and the tunnel barrier layer 220.Stated differently, the magnetic reference layer 210 and the tunnelbarrier layer 220 of the magnetic tunnel junction stack 200 locatedbelow the magnetic free layer 230 are recessed until a thickness of themagnetic reference layer 210 and the tunnel barrier layer 220 is equalto a thickness of the sidewall spacers 610 plus a thickness of themagnetic free layer 230.

The patterning process continues by recessing the bottom electrode 110.In an embodiment, an ion beam etch (IBE) can be performed to recess thebottom electrode 110 (i.e., electrode open), as depicted in the figure.

Referring now to FIG. 8 , a cross-sectional view of the memory device100 depicting forming a dielectric capping layer 840 is shown, accordingto an embodiment of the present disclosure.

The dielectric capping layer 840 is conformally deposited on the memorydevice 100. As depicted in the figure, portions of the dielectriccapping layer 840 perpendicular to the interconnect dielectric materiallayer 102 are located laterally adjacent to the bottom electrode 110,the magnetic reference layer 210, the tunnel barrier layer 220, sidewallspacers 601 and sidewalls of the hardmask layer 330. Portions of thedielectric capping layer 840 parallel to the interconnect dielectricmaterial layer 102 are located above the interconnect dielectricmaterial layer 102 and a top surface of the hardmask layer 330.Optionally, in another embodiment of the invention, the portions of thedielectric capping layer 840 parallel to the interconnect dielectricmaterial layer 102 are removed by a directional etch process such asRIE.

The dielectric capping layer 840 may be composed of any dielectricmaterial such as, for example, SiC, Si3N4, SiO2, a carbon doped oxide, anitrogen and hydrogen doped silicon carbide SiC(N,H) or multilayersthereof. The dielectric capping layer 840 can be formed utilizing aconventional deposition process such as, for example, chemical vapordeposition (CVD), plasma enhanced chemical vapor deposition (PECVD),chemical solution deposition, evaporation, or plasma enhanced atomiclayer deposition (PEALD).

Referring now to FIG. 9 , a cross-sectional view of the memory device100 depicting forming a dielectric filling layer 920 is shown, accordingto an embodiment of the present disclosure. Any suitable depositionprocess can be used to form the dielectric filling layer 920 in thememory device 100. The dielectric filling layer 920 may be made ofanalogous materials and formed in similar ways as the interconnectdielectric material layer 102. In some embodiments, a planarizationprocess may be conducted on the memory device 100 after deposition ofthe dielectric filling layer 920.

Therefore, by recessing the magnetic free layer 230 and forming thesidewalls spacers 610 on opposing sides of the magnetic free layer 230prior to patterning of the MTJ stack 200 and bottom electrode 110, backsputtering of metal particles can be prevented during subsequent etchingof bottom metal layers. More particularly, the laterally-recessedmagnetic free layer 230 surrounded by the sidewall spacers 610 confinesthe active MTJ region such that re-sputtering does not lead toelectrical shorts in the memory device 100, thereby improving devicereliability.

Further, embodiments of the present disclosure, may extend scalabilityof embedded MRAM devices and other embedded memory elements (such asRRAM) due to lack of tunnel barrier or metal-oxide device layer shorts.

Finally, embodiments of the present disclosure, provide a methodincluding a sequence of processing steps that can be conducted usingonly one chamber, thereby avoiding exposure of the MTJ stack 200 tooxygen. Specifically, the processing steps described in FIGS. 3-8 can beperformed in the same processing chamber, thus facilitating themanufacturing process, and reducing exposure of the MTJ stack 200 tooxygen.

The descriptions of the various embodiments of the present inventionhave been presented for purposes of illustration, but are not intendedto be exhaustive or limited to the embodiments disclosed. Manymodifications and variations will be apparent to those of ordinary skillin the art without departing from the scope of the describedembodiments. The terminology used herein was chosen to best explain theprinciples of the embodiments, the practical application or technicalimprovement over technologies found in the marketplace, or to enableothers of ordinary skill in the art to understand the embodimentsdisclosed herein.

What is claimed is:
 1. A method of forming a memory device, comprising:forming a bottom electrode above an electrically conductive structureembedded within an interconnect dielectric material; forming a magnetictunnel junction stack above the bottom electrode, wherein forming themagnetic tunnel junction stack includes: forming a magnetic referencelayer above the bottom electrode, forming a tunnel barrier layer abovethe magnetic reference layer, and forming a magnetic free layer abovethe tunnel barrier layer; recessing opposed lateral portions of themagnetic free layer; and forming sidewall spacers on the opposed lateralportions of the magnetic free layer for, at least in part, confining anactive region formed by the magnetic free layer and the tunnel barrierlayer.
 2. The method of claim 1, wherein the electrically conductivestructure further comprises a diffusion barrier liner located on abottom surface and lateral sidewalls of the electrically conductivestructure.
 3. The method of claim 1, wherein recessing the opposedlateral portions of the magnetic free layer further comprises: forming apatterned hardmask layer above the magnetic free layer; and etching theopposed lateral portions of the magnetic free layer.
 4. The method ofclaim 3, wherein the patterned hardmask layer comprises a metal as abottommost material, and a sacrificial dielectric material as a topmostmaterial.
 5. The method of claim 4, further comprising: removing thesacrificial dielectric material from the patterned hardmask layer. 6.The method of claim 3, wherein etching the opposed lateral portions ofthe magnetic free layer comprises conducting a dry etching technique. 7.The method of claim 3, further comprising: etching opposed lateralportions of the tunnel barrier layer located below the magnetic freelayer.
 8. The method of claim 1, further comprising: recessing themagnetic reference layer and the tunnel barrier layer of the magnetictunnel junction stack located below the magnetic free layer until athickness of the magnetic reference layer and the tunnel barrier layeris equal to a thickness of the sidewall spacers plus a thickness of themagnetic free layer.
 9. The method of claim 1, further comprising:recessing the bottom electrode.
 10. The method of claim 3, furthercomprising: conformally depositing a dielectric capping layer above themagnetic tunnel junction stack, above top surfaces of the patternedhardmask layer, and above top surfaces of the interconnect dielectricmaterial.
 11. The method of claim 10, further comprising: depositing adielectric filling layer above the dielectric capping layer.
 12. Themethod of claim 1, further comprising: forming a conductive layer abovethe bottom electrode, wherein a conductive material forming theconductive layer has a lower atomic weight than a conductive materialforming the bottom electrode.
 13. The method of claim 1, wherein themagnetic tunnel junction stack further comprises: a non-magnetic spacerlayer located on the magnetic free layer, a second magnetic free layerlocated on the non-magnetic spacer layer, and a magnetic tunnel junctioncap layer located on at least one of the magnetic free layer and thesecond magnetic free layer.
 14. A method of forming a memory device,comprising: forming a bottom electrode above an electrically conductivestructure, the electrically conductive structure being embedded withinan interconnect dielectric material; forming a diffusion barrier lineron a bottom surface and lateral sidewalls of the electrically conductivestructure; forming a magnetic tunnel junction stack above the bottomelectrode, wherein forming the magnetic tunnel junction stack includes:forming a magnetic reference layer above the bottom electrode, forming atunnel barrier layer above the magnetic reference layer, and forming amagnetic free layer above the tunnel barrier layer, the magnetic freelayer being laterally recessed with respect to the tunnel barrier layer;and forming sidewall spacers on opposed lateral portions of the magneticfree layer for, at least in part, confining an active region formed bythe magnetic free layer and the tunnel barrier layer.
 15. The method ofclaim 14, further comprising: forming a patterned hardmask layer abovethe magnetic free layer.
 16. The method of claim 15, wherein thepatterned hardmask layer comprises a metal as a bottommost material, anda sacrificial dielectric material as a topmost material.
 17. The methodof claim 14, wherein a thickness of the magnetic reference layer and thetunnel barrier layer is equal to a thickness of the sidewall spacersplus a thickness of the magnetic free layer.
 18. The method of claim 15,further comprising: a dielectric capping layer above the magnetic tunneljunction stack, above top surfaces of the patterned hardmask layer, andabove top surfaces of the interconnect dielectric material.
 19. Themethod of claim 18, further comprising: a dielectric filling above thedielectric capping layer.
 20. The method of claim 14, furthercomprising: forming a conductive layer above the bottom electrode,wherein a conductive material forming the conductive layer has a loweratomic weight than a conductive material forming the bottom electrode.21. The method of claim 14, wherein forming the magnetic tunnel junctionstack further comprises: forming a non-magnetic spacer layer located onthe magnetic free layer, a second magnetic free layer located on thenon-magnetic spacer layer, and a magnetic tunnel junction cap layerlocated on at least one of the magnetic free layer and the secondmagnetic free layer.
 22. A method of forming a memory device,comprising: forming a bottom electrode above an electrically conductivestructure embedded within an interconnect dielectric material; forming amagnetic tunnel junction stack above the bottom electrode, whereinforming the magnetic tunnel junction stack includes: forming a magneticreference layer above the bottom electrode; forming a tunnel barrierlayer above the magnetic reference layer; and forming a magnetic freelayer above the tunnel barrier layer; forming a patterned hardmask layerabove the magnetic free layer, the patterned hardmask layer being formedby a bottommost material including a conductive material, and a topmostmaterial including a sacrificial dielectric material; etching opposedlateral portions of the magnetic free layer; and forming sidewallspacers on the opposed lateral portions of the magnetic free layer for,at least in part, confining an active region formed by the magnetic freelayer and the tunnel barrier layer.
 23. The method of claim 22, whereinthe electrically conductive structure further comprises a diffusionbarrier liner located on a bottom surface and lateral sidewalls of theelectrically conductive structure.
 24. The method of claim 22, furthercomprising: removing the sacrificial dielectric material from thepatterned hardmask layer, the conductive material remaining in thememory device; etching opposed lateral portions of the tunnel barrierlayer located below the magnetic free layer; and recessing the magneticreference layer and the tunnel barrier layer of the magnetic tunneljunction stack located below the magnetic free layer until a thicknessof the magnetic reference layer and the tunnel barrier layer is equal toa thickness of the sidewall spacers plus a thickness of the magneticfree layer.
 25. The method of claim 24, further comprising: recessingthe bottom electrode; conformally depositing a dielectric capping layerabove the magnetic tunnel junction stack, above top surfaces of thepatterned hardmask layer, and above top surfaces of the interconnectdielectric material; and depositing a dielectric filling layer above thedielectric capping layer.